○ New Things I Learned
I learned why IP addresses are divided into four parts (e.g., 0000.0000.0000.0000).
I understood the relationship between hostnames and IP addresses.
I finally understood what IPv4, IPv6, and DNS—terms often seen in router settings—actually mean.
○ IP Address
An IP address is an address system used by the IP protocol at the network layer to identify individual hosts.
It consists of 32 binary bits and is usually divided into four 8-bit sections, expressed in decimal format (e.g., 1111.1111.1111.1111).
This commonly used format is called IPv4, where “v4” stands for “version 4.”
However, with the rapid expansion of the Internet, a more scalable address system became necessary—this led to the development of IPv6.
IPv6 is composed of 128 bits, divided into eight 16-bit blocks. Each block is expressed as four-digit hexadecimal numbers (ranging from 0 to FFFF).
In most home networks and small websites, IPv4 is still more widely used. Therefore, both IPv4 and IPv6 are often used together in a configuration called Dual Stack.
○ Hostname
To connect to a specific host on the Internet, you need its IP address.
However, users prefer to use easily recognizable and meaningful text-based names instead of numeric IP addresses.
That’s why when a user enters a hostname, a DNS (Domain Name System) server translates it into the corresponding IP address.
A DNS structure is typically divided into four hierarchical levels: Country Domain, Organization Type, Organization Name, and Host, separated by dots (.).
- Example:
→ www (Host), google (Organization Name), co (Organization Type), kr (Country Domain)
- Note: The term hostname can refer to the entire name (www.google.co.kr), or in a narrower sense, it may specifically refer to the host part (e.g., www for a web server).